The present invention relates generally to timepieces, such as wristwatches, and in particular, to improved constructions and methodologies for maintaining accurate date and/or day information, in such timepieces that comprise a date and/or day ring, such as those timepieces typically referred to as “analog” or “quartz-analog” watches having hands for displaying time, and which drive the date ring as a function of the rotation of one or more gears (or “wheels”), such as (by way of example) the wheel that is coupled to the hour hand. In particular, the present invention provides an improved construction and methodology for maintaining an accurate date and/or day display even if the hour/minute hands are mechanically and/or electrically decoupled from the date display assembly.
That is, in a conventional quartz analog timepiece, the stopping of the hour/minute hands typically results in an inability of the date ring from rotating, thus leading to a loss of accurately displayed date and (possibly) day information. Moreover, if the hands are disengaged or otherwise stopped for a significant amount of time (e.g. days or weeks), any calendar date ring would have to be significantly readjusted (e.g. manually), a problem that becomes even more significant if the timepiece includes a month or day display or other perpetual calendar features. Although such disengagement of the hands may occur only momentarily or for short durations due to inadvertence or time setting, users may also intentionally disengage or otherwise stop the hands on the assumption that energy is being conserved.
Attempts have been made to overcome the foregoing perceived deficiencies. For example, in at least one known “perpetual calendar” watch design, the hands and the calendar ring are driven directly by motors that are controlled by a microprocessor. In such a construction, every step of every motor is processed and maintained by the microprocessor, such that every position of every hand, as well as the positioning of the day/date ring, is maintained by the microprocessor. Such a construction does not require any “midnight” detector even if the hands are stopped, since the microcontroller always knows and controls the position of the hands and day/date ring when running and/or how long they have been disengaged or otherwise stopped. However, all hand-setting functionality must therefore also be controlled by the microprocessor. And, for a three-hand (e.g. hour, minute, second) display, at least two (2) motors would be required, thus complicating the time setting and/or date readjusting operations, as would be understood and appreciated by one skilled in the art.
At least one other approach to the concept of a “perpetual calendar” watch has been put forth, whereby the hands are driven by only one motor, as in a “standard” quartz analog movement, thus allowing for mechanical and manual hand setting. In this implementation however, a 24-hour or “midnight” detector is needed to control the rotational advancement of the date ring. Disadvantageously, while the hands are stopped, there is no continuing signal to tell the microcontroller to rotate the date ring, thus maintaining the perceived deficiencies stated above. Moreover, the perceived deficiencies with this construction are increased when one extends the functionality to the incorporation of a day disc, which during normal operation, rotates in synchronization with the hour hand. Upon the stoppage of the hands for a long period of time, the discrepancies between the accuracies of these two rings (day and date) become even further pronounced. Complicated constructions have been used to attempt to deal with these and other problems, and the reader may wish to review U.S. Pat. Nos. 6,088,302; 6,582,118; and 6,584,040 (collectively the “Seiko patents”) in this regard. To the extent that such subject matter does not conflict with the invention disclosed herein, the disclosure of the Seiko patents is incorporated by reference as if fully set forth herein.
Another deficiency in the prior art is the inability to adequately and accurately maintain (or update) the display of the proper day on a day ring, in the event that the hands of the timepiece are stopped. Moreover, adjusting the day by a typical hand-setting operation thereafter will tend to further misadjust the date being displayed on the date ring since the typical synchronization between the hands and the date and day rings does not typically allow for independent calibration. This is a problem that is also overcome by the present invention.
Accordingly, it is desirable to provide a timepiece with an improved calendar function that overcomes the perceived deficiencies in the prior art noted above and further achieves the aforementioned and below mentioned objectives.